Field of the Invention
The invention relates to a metering device for the conveyance of small substance quantities out of a reservoir into an application space by a diaphragm micropump that can be used, in particular, for the conveyance of small doses of gases (aromas).
In microsystem technology, micropumps are used in many sectors as special actuators. Their use makes it possible to convey minimal quantities of a gas or of a liquid in exactly dimensioned doses. In addition to use in laboratory technology, micropumps are also employed in modern office technology, and, in this context, a large proportion of their use is in ink-jet printers. These micropumps are distinguished by a compact form of construction and high metering accuracy that is achieved by the use of new materials and by the pumping element acting directly on the substances to be conveyed.
The same object of releasing minimal substance quantities is found in aromatization, such as is carried out, for example, during the drying operation in laundry dryers. In addition of aromatics, at the present time, aromatic cloths are used or plastic containers containing the aromatic that distributes the aroma by evaporation are used. In both instances, the discharge of the aroma takes place in a relatively uncontrolled way, either by the choice of a suitable size of the aromatic cloths or by a suitable dimensioning of the orifice cross-section of the containers. Both methods are, therefore, subject to pronounced fluctuations as a function of the temperature. Moreover, their application is not very user-friendly, and an unnecessary amount of consumable material occurs. However, the use of conventional micropumps that do not have the disadvantages just mentioned, has not gained acceptance because the accuracy that these offer is not necessary in aromatization and, therefore, the use of the costly high-precision pumps is not justified. However, because the aromatic essences are very costly, a sparing demand-controlled application is a plainly desirable aim.